Combined resonant shunt device for telegraph circuits



March 22, 1927.

H. NYQUIST comsmsn RESONANT SHUNT mzvrcm FOR TELEGRAPH cmcun's Fil ed June 27, 1925 IN VENTOR my '5;

Q ATTORNEY telegraph relay.

Patented Mar. 2 2, 1927.

% we STATES trio-1 HARRY NYQUIST, OF ELMHURST, NEW YOBK, ASSIGNOR 'I O AMERICAN TELEPHONE AND TELEGRAPH COMPANY, A CORPORATION OF NEH? YORK; i

COM INED nnsonanr strum DEVICE non TELEGRAPHCIRCUITS.

Application filed June. 27, 1923. Serial No. 6483367.

7 This invention relates to transmission lines and more particularly to arrangements for preventing interference between different types of currents utilized on such lines.

Then a transmission line is composited for both telegraph, teiephone and signaling purposes it is necessary to make special provision to, prevent interference from the out-. going signaling current and the receiving Ordinarily this might be accomplished by connecting a resonant shunt across the'line between the composite set and the relay windings and a similar shunt across the line between the relay windings and balancing apparatus for purposes of balance. It has been found in practice that such separate shunts are open to the objections that the coils have an undesirable reaction on the outgoing telegraph wave and furthermore I are required. In the arrangements of this invention the above objections and disadvantages are overcome and interference between the different currents and apparatus is prevented by utilizing a combined resonant shunt connected acrossthe circuit on each side of the telegraph relay and having a single coil with'two windings and with the elements of the shunt arranged and proportioned as pointed out hereinafter. Other features of the invention will appear more fully from the detailed description hereinafter given. 7

The invention maybe more fully understood from the following description together with the accompanying drawing in which is illustrated a circuit diagram of the invention. 7

In the drawing is shown a portion of a transmission line L terminating in a composite set 13. Associated with the composite set is a circuit 14 which might be connected with a composite ringer including a source of signaling current, such for example as 135 N current, which is suitable for transmission out over the line L. Associated with the composite set is a telegraph circuit which includes the windings of a telegraph relay 15. The terminals of the windings of relay 15" are numbered 1 to 8 inclusive. These windings are supposed to be arranged so that current froman odd to an even terminal produces magnetization of the same kind. The windings of relay 15 through its armature control the sounder 16 to indicate in addition control current transmitted over anotherlme section. The network N is provided for purposes of balance. Bridged the incoming telegraph impulses and may I relay 19 and" key 18 whereby battery of opposite polarity may be connected to the line Toprevent the signaling currents from circuit 1 L from interfering with thetelegraph relay 15 there is bridged across the telegraph circuit on each side of the'relay wind ings the combined resonant shunt of this in: vention. This shunt includes the circuit 21 and the circuit 24. Circuit 21includes'winding 22 and condenser 23. 1 Circuit 24 includes winding 25 and condenser 26. These two windings are made up of an equal numberof turns and comprise'a single coil rather than Q separate coils as-in former arrangements.

The terminals of the windings are numbered 9, 10, 11, and 12 as shown. i The windings are poled as indicated by the numerals of these terminals. In other words current from an odd to an even terminal will produce magnetization of the same kind. The con- 7 to each other and so that both condensersin series will resonate with both windings 22 and 25 in series aiding-at the particular-interfering frequency, such as in this instance the frequency of the-signaling current illus-' densers 23 and 26 are chosenso as to be equal trated as 135 N. Under these conditions i the shunt will eifeetually prevent any of the signaling currentfrom interfering with the telegraph relay. As far as the outgoing telegraph Wave is concerned it will be apparent that it passes through the two windings 22 and 25 in such a way as to cause magnetic effects of opposite sign. Consequently there is no net magnetizing effect and the coil acts I certain specific arrangements which are deemed desirable, it is understood that it is capable of embodiment in many and otherhile the invention has been disclosed in r widely varied forms Without departing from the spirit of the invention as defined by the appended claims.

a What is claimed-is:

' 1. A transmission line including a composite set, a circuit associated with said line through said composite set and includinga source of signaling curren a telegraph circuit associated with said line through said composite set, relay windings in said telegraph circuit, means for applying outgoing telegraph current to the midpoints of said relay windings, and separate shunt circuits connected across said telegraph circuit on each side of said relay windings, each of said shunt circuits comprising a winding and condenser connected in series therein whereby said shunt circuits will be resonant at the frequency of said signaling current, said windings being mounted on a common core and being poled so hat said outgoingtelegrap'l' currents will cause no net magnetization effect in said windings.

2. A transmission line including a composite set, a circuit associated with said line through said composite set and including a source of signaling current, a telegraph circuit' associated with said line through said composite set, relay windings in said telegraph circuit means for applying outgoing telegraph current to the midpoints of said relay windings, and separate shunt circuits connected across said telegraph circuit on each side ofsaid relay windings, each of said shunt circuits comprising a windin and condenser connected in series therein whereby said shunt circuits will be resonant at the frequency of said signaling current, said windings being mounted on a common core and being poled so that they will cause substantially no efiect on said outgoing telegraph currents. a

3. A transmission line, a balancing network, a transmitting means and a receiving means associated With said line, said transmitting and said receiving means being in conjugate relation, separate circuits bridged across said line on the line and network sides of said receiving means, each of said circuits comprising inductance and capacity so arranged and so proportioned With respect to each other that said circuits will be resonant at a certain frequency coming in over said line and together will be substantially equivalent to a bridged capacity with respect to the currents transmitted to said line from said transmitting means.

4. A transmission line including a 'composite set, a circuit associated With said line through said composite set and including a source of signaling current, a telegraph circuit associated with said line through said composite set, relay windings in Said telegraph circuit, means for applying outgoing telegraph current to the midpoints of said relay windings, and separate shunt circuits connected across said telegraph circuit on each side of said relay windings, each'of said shunt circuits comprising a winding and condenser connected in series therein wherebysaid circuits Willbe resonant at the frequency of said signaling current, said Windings being mounted on a common core and being so arranged that the magnetic effects produced therein by said outgoing telegraph currents will be of opposite sign.

In testimony whereof, I have signed my name to this specification this 26th day of June, 1928. I I

HARRY NYQUIST, 

